An aspiring designer drunkenly fell to her death from a four-story Williamsburg rooftop early Friday when her angry boyfriend locked her out of his pad during a fight, law enforcement sources said.

Hannah Shaw, 29, a beautiful blonde transplant from Maine, had been out drinking with boyfriend Alex Douglas, 42, at the dive Lucky Dog on Bedford Avenue when they got into an argument, sources said.

“She was drinking with her boyfriend all night,” a law enforcement source said about Shaw, who worked in landscaping but also designed jewelry and clothing out of garbage bags.

Douglas and his pals headed back to his apartment in a Kent Avenue building — but he wouldn’t let her in, the sources said.

Shaw, a 2007 graduate of Hampshire College in Amherst, Mass., then climbed onto the roof, but lost her footing and fell three stories to an adjoining rooftop, sources said.

“He locked her out. She went up to the roof and fell off,” the source said.

Someone called 911 and cops found Shaw splayed out unconscious. An EMS crew rushed her to Woodhull Hospital, where she was pronounced dead.

Douglas refused to comment, only telling The Post, “That was my girlfriend!” and slamming the door.

Shaw had been working as a garden manager at a Williamsburg-based landscaping company, Jungle Design NYC, where a co-worker said she dated Douglas for about a year.

“Hannah was such a dear person. She was so overly helpful and great to be around,” the co-worker said.

Shaw was a talented designer, another pal said.

“She created dresses out of garbage bags,” said Sylvia Holden, a fashion stylist who used her clothing. “Whenever I needed something she always came through. She lent me tons and tons of clothing.”

A roommate was floored by her friend’s death.

“This is just a really tragic accident. She was a lovely roommate. She was always happy and so kind and caring so much,” said Ada Vesti, 34, a Swedish book publisher who lived with Shaw and another woman in a South 4th Street apartment.